A bit unusual career path, there are two things you are asking about
1. Ortho residency: Apply through ERAS, with great scores and hands on USCE. Very competitive not usually easy to get as an IMG even if you do not need visa. But then america is a land of dreams, try if that is what you really want in life.
2. Peds Ortho fellowship: You need ACGME accredited residency in orthopedics in US before applying, or atleast 4-5 years of orthopedic(residency + SRship) in India before you even apply. Then take your USMLE's and hope they do not change the rules. Right now they are trying to close that door for IMG's also, you need an approval proving you are exceptional candidate for fellowship if you are an IMG.
If you are spouse is in US depending on their status citizenship/green card/ H1/J1 your work authorisation might be faster, but I think being IMG is a big issue these days then getting a Visa.